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  #1  
Old Fri 20 March 2009, 15:39
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
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Milwaukee Router weirdness - SSR (solid state relay) not suitable

Hi Guys,

While not specifically a MM question I thought I'd ask since others of you are using the Milwaukee 5625 router in your machines.

The problem is this: When I start a job the Gcode turns the router on and it runs fine for about 2 minutes. Then, after about two minutes of cutting, the router appears to slow down and change it's sound rather drastically from it's usual high pitched whine to a much lower pitched sound.
The cut seems to suffer no quality loss but it sounds strange to me.

Is this something you guys have experienced and is it normal? Is it due to the router bearings warming up or just too much load?

I just restarted the job and ran it as an air-cut job (no load on the router) and couldn't get the problem to reproduce.

This leads me to suspect the issue is with the router itself (if it is, indeed, an issue at all) rather than the control box.

The details:
Material being cut: 1/2" MDF
Router Speed: 15K RPM
Feedrate: 60in./min.
Router is powered via an SSR in the control box: Magnecraft SSR225DIN-DC
SSR Control is connected to PMDX-122 J8-Pin14 and +5Aux out.
Control SW is Mach3 R3.042.020

The one thing I have not tried is plugging the router directly into the wall
(Bypassing the SSR) to see if the problem persists. I'll do that as soon
as my day job conference call is over...

I wanted to get you guys' thoughts on this while I continued debugging.

Ideas? Recommendations?

Many thanks!

-Jeff
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  #2  
Old Fri 20 March 2009, 18:14
sailfl
Just call me: Nils #12
 
Winter Park, FL
United States of America
Jeff,

I have a Milwaukee router and I have not experienced any problems. I am not using a RSS.

Have you tried turning on the router from Mach with out running GCode to see what happens? You can push the spindle button and it will turn on. That would give you an idea if you experience the same problem.
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  #3  
Old Fri 20 March 2009, 21:47
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
Send a message via Yahoo to jeffh
Yeah, that's a good point Nils, I haven't tried running it without GCode
I'll give that a try and report back what I find.

So you never hear your router radically change it's sound (and presumably it's
speed) when running a job?

Thanks for the tip!

-Jeff
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  #4  
Old Fri 20 March 2009, 22:59
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by jeffh View Post
. . . . after about two minutes of cutting, the router appears to slow down and change it's sound rather drastically from it's usual high pitched whine to a much lower pitched sound.
The cut seems to suffer no quality loss . . . . . .
If the speed was indeed changing, you should see it in the cut quality.

How old is this router? Wondering about the brushes and/or bearings.....
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  #5  
Old Sat 21 March 2009, 08:42
normand blais
Just call me: Normand
 
montreal
Canada
Hi Jeff
I just got one milwauke router and got the same speed slow down .Once it even slowdown so much that the bit broke . I use that blue gum to stick picture on wall and put it on the speed control switch to stop it from vibrating . It seem ok now but I think I should get it fix
Normand
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  #6  
Old Sat 21 March 2009, 10:09
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Jeff,

It's interesting that the router speed slows down. You have the router set at the minimum speed (15K rpm) already.

I have been running my Milwaukee 5625 for quite some time now, with no problems or issues. Well ... had one problem, but it was operator error

At 15K rpm, the router does not produce a high pitch sound. At that low speed, the noise is minimal and I don't wear hearing protection.
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  #7  
Old Sat 21 March 2009, 17:01
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
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Hi all,

Sorry for the late response... ran into some honey-do list turbulence.

I've just run the pattern with the router plugged directly into the wall and
I saw no slowdown or any errant behavior... I'll re-setup the machine as normal and rerun the pattern again just to make sure I'M not the one with the errant behavior.

I do start to wonder if it was simply a dense part of a sheet of MDF? seems like the sheets would be fairly uniform but... who knows.

I also know painfully little about SSR's and I'm wondering what happens if the control output from the BOB happens to toggle fast enough (for some reason) if it will actually modulate the load output and produce a lower and choppy power voltage?

More details:

The router is brand new, purchased in late January of this year so I'm hoping
it's not the bearings already. It's probably only got 10 hours on it total. If it is the bearings they don't look to hard to replace.

I have a pattern where I can run the gcode without turning the router on from within Mach3 so I'll run that if the problem shows back up.

I've got the router speed control set at "5" which should be 14-16K RPM
based on the little speed guide on the side of the router.

I'll continue messing with it... thanks for all the tips and things to think about.

-Jeff
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  #8  
Old Sat 21 March 2009, 18:20
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Yes, the SSR could modulate the power output. Not the voltage, but chopping as you indicated above.

Three far fetched theories to add to the mix:

1) The SSR control signal is marginal, and as things heat up, the SSR starts toggling.

2) The SSR has an internal thermal cutout circuit that is toggling.

3) The SSR has a weak thyristor (special transistor) that is only conducting half of the AC cycle after it heats up.

For all of these, it would be helpful to know the specifications of your SSR, how much it is heating up when operating, and what the measured voltage of the control signal to the SSR is before and during the problem condition.

Again, these are somewhat far fetched.
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  #9  
Old Sun 22 March 2009, 12:48
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
Send a message via Yahoo to jeffh
Thanks Brad!

It just so happens that "Far fetched" is my middle name!

I don't have a scope here at home but I'll throw a meter on the outputs and see if I can capture any change (It'll be RMS but if a change is significant enough I should be able to capture it).
I've instrumented up the control box so when I do get a scope here I can watch the SSR control signal and see if it starts acting strange.

I'm trying to create a small testcase where I can reproduce the problem on a small piece of code in the event there's something obvious in the code structure.

I'll dig up the specs on the SSR and post them.
I'm hoping the problem is just operator error or operator over-exuberance.

Thanks Brad
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  #10  
Old Sun 22 March 2009, 19:42
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
I've used a lot of Solid State Relays in various projects and never had one cause this kind of problem. Given the assumption that your SSR is a standard unit with zero-voltage crossing detection (meaning that it turns on and off when the AC sine wave crosses the 0-voltage point) and given the assumption that your SSR has a standard 3-32VDC control side running with the positive (+) terminal connected to +5V and the negative (-) terminal connected to the control signal, it should work without any side-effects.

Where I HAVE had problems with an SSR is when the load was too light for the relay. An SSR needs to have a load. Also, an SSR never truly turns off. In the Off State, you can still get a shock, because of leakage. Neither problem area would seem to be present with your router.

A router with soft-start electronics comes on gradually, but if it comes on at all, it proves that it had enough of a load for the SSR to work. An SSR does not vary the voltage, in other words, it is not a speed control, so it should not interfere with the soft-start speed-control circuitry on the router.

I would guess that you either have a physical problem developing in the router (worn bearings or brushes) or an electrical problem with the soft-start board or a physical problem with the electricity (undersized wiring or unstable AC voltage supply).

If you are cutting at a reasonable depth and a reasonable speed so that the router is not overheating and bogging down because it is expected to do more than it was designed to do, a router should be able to cut all day long without bogging down.

Have you tried to swap out the router with another unit? I know that most of us are on a budget and don't have extra routers laying around, but having a spare is more than just a luxury. Before I installed a spindle, I had two Port-Cable routers. I still have both Porter-Cable routers to be used if the spindle has a problem.
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  #11  
Old Sun 22 March 2009, 21:54
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
A while back I used a 2.5 Amp rated SSR to control 3x 150 Watt outdoor spotlights (incandescent halogen) on a 230Volt circuit. The lights burned at less than full brightness and the SSR was replaced for an old-fashioned relay, which cured the problem. Can't explain it, but it happened.
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  #12  
Old Mon 23 March 2009, 12:08
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
Send a message via Yahoo to jeffh
Thanks Mike and Gerald,

I do have another Router I can swap in (A lightly powered Porter-Cable router) but it'll take some shimming. The one advantage to this second router is it's a single speed, no frills router so it would eliminate a couple
of variables from the problem.

I had thought that it might be the material that was causing the change in sound/speed but yesterday I watched as the router "Shifted gears" while
mid-jog from one part of the cut pattern to the next.... I'm pretty convinced now that it's NOT material related.

I also happened to be holding a meter with the leads plugged into the same power as the router and when the sound/speed change occured I noticed only a tenth of a drop in AC voltage so it would appear that the output voltage of the SSR stays constant (relatively).

I'm going to go back to plugging the router into the wall and re-try the cut to see if I can make the problem happen again under different circumstances. My next resort will be to replace the SSR with a standard relay as Gerald suggests and as others have done.

I like the SSRs but I can't help but think that the soft-start + variable speed
control electronics of the router might be impacted by the SSR's own internal electronic behaviour, particularly the fact that the drain never fully closes and some current leaks out to the load...

I'll keep you all posted and many thanks for the helpful advice!

-Jeff
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  #13  
Old Mon 23 March 2009, 14:58
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
I wouldn't expect for you to be able to see much of a change at the output of the SSR; I'm curious if you see any change at the control input.

If there's a change at the input, it implies something funny happening in the circuitry driving the SSR. If there isn't, it implies faulty, or mis-speced SSR.
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  #14  
Old Mon 23 March 2009, 19:33
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
Send a message via Yahoo to jeffh
Yeah I didn't really expect to see much either... and I wasn't disappointed.

I'll try and capture the control signal to the SSR. I really need a scope
for this though. As you well know the handheld meters just don't tell
the whole story.

The other thing I'll do is put another router or maybe even just an incandescent
light fixture in place of the Milwaukee and see if the same results occur.

Unfortunately, this type of setup requires the swap-in/swap-out debug
methodology and I just haven't had a chance to start trying enough things
to cause the problem to expose itself.

First rule of debugging: Understand the problem // Not there yet!

Thanks Brad!
-Jeff
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  #15  
Old Tue 24 March 2009, 00:19
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
My preferred "relay" to drive a router is a contactor, similar or identical to the e-stop contactor. They have a longer life than typical relays.
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  #16  
Old Tue 24 March 2009, 22:41
Roadkill_321
Just call me: John #7
 
Wiseton, Saskatchewan
Canada
Jeff,

I have exactly the same setup as you and I have had no problems whatsoever. Been running this setup now for about a year now and no problems. Sorry I don't have any suggestions, but I figured I'd let you know that that combo does work.

John
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  #17  
Old Wed 25 March 2009, 10:51
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
Send a message via Yahoo to jeffh
Thanks John,

I didn't know if I had stumbled across a relay-router combination that just wouldn't work so it's good to hear there's a successful implementation.

The problem I have is frustratingly intermittent.

I will ultimately probably switch out to a mechanical relay/contactor just
to be sure the problem is gone...

I do want to try a bunch of the other suggestions though before I put the fix
in place just to gather the data and possibly help someone else out in the future. The dang day job just keeps getting in my way

-Jeff
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  #18  
Old Wed 25 March 2009, 22:45
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Jeff,

Same response as John. My setup has been operating without any issues.

Interesting thread.
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  #19  
Old Thu 26 March 2009, 04:35
javeria
Just call me: Irfan #33
 
Bangalore
India
Add me in - working for almost 6 months without a wink now
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  #20  
Old Thu 26 March 2009, 04:49
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Just a thought; how is your PMDX-122 powered? Has it got enough "oomf" to keep the ssr powered on properly?
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  #21  
Old Thu 26 March 2009, 07:34
javeria
Just call me: Irfan #33
 
Bangalore
India
Yes G' that's right - if the PMDX is powered by the USB - it might be a problem then - but not sure about this though.
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  #22  
Old Thu 26 March 2009, 11:12
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
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Hmmm that might be something to think about...

The PMDX is powered off of a 12v/2A supply so it should have plenty
of oompf to drive most things. However, the SSR has a 3v-32v DC control
and I'm driving that with a 5v nominal output from the PMDX (it's actually
about 4.6v).

It seems like there should be enough current supplied at 4.6v to keep the control electronics open (forward biased) however, I'm not a power electronics guy so I'm not sure of 1) the real threshold voltage for these power gates and B) the bias current requirements for the gates. I could be dangerously close to the threshold and that could be causing the problem.

How are the rest of you guys that have the same SSR driving it?
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  #23  
Old Thu 26 March 2009, 11:24
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
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I just went and checked the SSR control circuit that I've got... and, well
I'm not really sure what I was thinking when I wired this up but here it is:

I have PMDX:J8:[pin14] connected to the SSR control "-" pin
I have PMDS:J8:[+5 Aux out] connected to the SSR Control "+" pin

I have Mach3 configured to drive the PMDX:J8:[pin 14] active low which then presents a delta voltage of ~5v on the control pins and activates the relay.

What I don't know: (is a long list but here's the pertinent pieces )

1) What is the current sourced by the PMDX +5v aux output
2) What is the current required by the SSR control to fully open the gate and keep it open.

I have some meetings this morning so I have ample time to dig into these questions :-)

I'm thinking that supplying the SSR with a +5V direct from the power supply rather than from the PMDX would be better as it would certainly provide the required current (If that's the problem).

How are you guys connecting up your SSRs?

Many many thanks everyone!!!

-Jeff
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  #24  
Old Thu 26 March 2009, 11:43
javeria
Just call me: Irfan #33
 
Bangalore
India
I have a miniIO from candcnc.com - there is small transistor (3904 I think) which switches the SSR,
chk this on pminmo website

http://pminmo.com/PMinMOwiki/index.p...interface#AUX1
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  #25  
Old Thu 26 March 2009, 11:56
javeria
Just call me: Irfan #33
 
Bangalore
India
Jeff - alternatively try using the on-board relay to switch the SSR - us the 12v thru the relay to the SSR.
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  #26  
Old Thu 26 March 2009, 12:27
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
You have the control terminals of the SSR connected properly. The (+) side is connected directly to a voltage source and the (-) side is connected to the TTL gate. When the TTL turns ON (Active LOW or 0vdc), about 10mA passes through the internal LED inside the SSR.

The PMDX-122 can sink or source 16mA per input/output, so you have plenty of current available for the SSR's LED.
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  #27  
Old Thu 26 March 2009, 13:03
jeffh
Just call me: Jeff #21
 
Bellingham WA
United States of America
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Thanks for the confirmation Mike, and Irfan, that's a great idea and one that
is trivial to wire up.

My plan of attack for lunch today is:

1) Attempt to get the problem to manifest on a reproducible basis

2) Wire up the 12v through the PMDX onboard relay and use that to control
the SSR. As Mike says, the SSR control is optically activated and a very small amount of current is required to turn the LED on so I don't expect this will help but it will rule out other things.

3) Swap out the Milwaukee for another router that has no speed control
other than on or off. If no problem is encountered with the simple router then I think the Milwaukee router is the problem.

4) If the problem persists with the simpler router, I'll replace the SSR with a contactor relay.

Should keep me out of trouble today.

Thanks for all the help guys!

-Jeff
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